1. Field of the Invention
The present invention relates to a structure inspection method of inspecting the structure of an evaluation object from an intensity of reflection light of the evaluation object. Further, the present invention relates to pattern formation method, process condition determination method and resist pattern evaluation apparatus.
2. Description of the Related Art
Many reports with respect to the following method have been made. According to the method, a light incident on a pattern having a regular structure on a substrate, and the light is diffracted to obtain a diffraction light. Then, the dimension and shape of the pattern are evaluated from the measured result of the obtained diffraction light. For example, U.S. Pat. No. 5,963,329 discloses the method given below. According to the method, cos Δ and tan ψ of a pattern having a regular structure are measured using an ellipsometer. Then, the measured values are compared with cos Δ and tan ψ obtained from a theoretical electromagnetic wave calculation to determine the dimension. In the method, the theoretical calculation is made using the structure of a film forming a substrate and optical constant. In this case, the method is applicable to evaluation for resist pattern after development and pattern after etching. However, if the method is used for evaluating the dimension of resist pattern such that a developer film is formed on the substrate, it is impossible to accurately evaluate the pattern. This is because a mixed phase of resist reaction product and the developer exists in the vicinity of the resist pattern. According to the method disclosed in JPN. PAT. APPLN. KOKAI Publication No. 2002-25883, it is difficult to accurately evaluate the pattern. This is because a mixed phase of resist near the resist pattern and the developer is not considered like the U.S. Pat. No. 5,963,329 mentioned above.
The U.S. Pat. No. 5,963,329 further has the following disclosure. That is, theoretical wavelength dispersion of the diffraction light intensity is previously obtained by electromagnetic wave calculation using the structure of a film on the substrate and optical constant. Then, a comparison between the measured result of wavelength dispersion of the diffraction light in an actual substrate and the preceding theoretical wavelength dispersion is made to calculate the dimension and shape. This U.S. patent has disclosure of considering a composition distribution in the depth direction of the film caused by doping, and does not disclose the distribution features.
Therefore, it is impossible to accurately evaluate the pattern using the conventional method of diffracting light incident on a pattern having regular structure on a substrate, and evaluating the dimension and shape from the measured result of the obtained diffraction light.